Build Your Own Planet

Design a world from scratch • Set size, atmosphere, water & more • See if life could survive

Size & Mass
Radius1.0 x Earth
Core DensityIron-Silicate
Axial Tilt23 deg
Star & Orbit
Distance from Star1.0 AU
Orbital Eccentricity0.02 (nearly circular)
Star Type
Atmosphere
Atmospheric Pressure1.0 atm
Greenhouse GasesModerate
Magnetic FieldEarth-like
Atmosphere Type
Surface & Ocean
Ocean Coverage71%
Volcanic ActivityModerate
Rotation Speed24 hrs
Surface Color

How the Simulator Works

Size and Gravity
Larger planets have stronger gravity. Too much gravity collapses complex molecules; too little and the atmosphere bleeds away into space.
Habitable Zone
Each star type has a different "Goldilocks zone" where liquid water can exist. The hotter the star, the farther out that zone sits.
Greenhouse Effect
More greenhouse gases = warmer surface. Venus has a runaway greenhouse effect at 465 C. Earth's balance is why life thrives here.
Magnetic Field
A planet's magnetic field shields life from deadly solar radiation. Mars lost its field - and then lost its atmosphere and any chance for life.

About the Build Your Own Planet Simulator

Welcome to the ultimate Build Your Own Planet Simulator! Have you ever wondered what it takes to create a habitable world? This interactive astrophysics sandbox lets you play the role of a cosmic architect. Start by adjusting your planet's size, mass, and core density, then position it around a specific type of star to find the perfect Goldilocks zone. You can fine-tune atmospheric pressure, greenhouse gases, magnetic fields, and water coverage to see how these delicate variables interact. Once your design is complete, generate a full Science Report to find out if your custom world is a dead, frozen rock, a toxic greenhouse, or a Class I Earth Analog capable of supporting complex life!

Understanding the delicate balance of planetary science is just the beginning of your cosmic journey. If you want to explore the real planets in our neighborhood, check out the Interactive Solar System. To dive deeper into the physics of how planets and moons interact with one another, experiment with our Gravity Orbit Physics Simulator or track the celestial shadows in the Eclipse Visualizer Tool.

Planetary science also requires a deep understanding of the chemical building blocks of the universe. Brush up on your elemental knowledge with the Interactive Periodic Table. Whether you are a student learning about planetary habitability or a sci-fi writer designing a new world, FlipNSpin offers the best free interactive science tools to spark your imagination.